The invention relates to a method and an arrangement for adjusting output power of a transmitter power supply, the transmitter being typically a transmitter of a base station.
Transmitters used in radio communication comprise a power supply, which supplies a transmitter with the power it requires. Situations often occur where the transmission power of the transmitter varies rapidly. These rapid variations in the transmission power of the transmitter cause rapid variations of charge in the output of the transmitter power supply. In a prior art solution, the output power of a transmitter power supply is measured, and on the basis of this measurement, a chopper controlling the operation of the power supply is controlled by a power supply control unit. Adaptations to variations of charge require relatively many chopper periods, due to which the prior art solution does not enable the adaptation to rapid variations of charge. Increasing the chopper frequency would accelerate the adaptation but it would also cause the problem that the efficiency of the power supply easily impairs too much. For example, if the chopper frequency is doubled, the power loss of the power supply will be doubled as well. A problem in the prior art solutions is also that the response of parallel connected power supplies is difficult to control.
It is thus an object of the invention to provide a method and an apparatus implementing the method to solve the above problems. This is achieved by a method of adjusting output power of a transmitter power supply. In the method, the output power of the power supply is measured and the output power of the power supply is adjusted on the basis of the measured output power. The output power of the transmitter power supply is adjusted on the basis of the transmission power of the transmitter such that a power supply control unit receives from the transmitter a synchronisation chopping that synchronizes the operation between the transmitter and the power supply control unit, and the power supply control unit receives from the transmitter the information on the transmission power of the transmitter.
The invention also relates to an arrangement for adjusting output power of a transmitter power supply. The arrangement comprises a transmitter power supply comprising a chopper and a power supply control unit in feedback between the power supply output and input to adjust the output power of the power supply on the basis of the measured output power of the power supply. The power supply control unit is arranged to adjust the output power of the power supply on the basis of the transmission power of the transmitter such that the power supply control unit is arranged to receive from the transmitter a synchronisation chopping that synchronizes the operation between the transmitter and the power supply control unit, and the power supply control unit is arranged to receive from the transmitter the information on the transmission power of the transmitter.
The preferred embodiments of the invention are disclosed in the dependent claims.
The invention is based on the idea that the power supply control unit receives from the transmitter a synchronisation chopping and the information on the transmission power of the transmitter. The synchronisation chopping synchronizes the operation between the transmitter and the power supply control unit. On the basis of the above and of the output power of the power supply, measured from the power supply output, the power supply control unit adjusts the output power of the transmitter power supply.
The method and arrangement of the invention provide a plurality of advantages. The output power of the transmitter power supply is adapted to the respective transmission power of the transmitter. A significant advantage of the invention is also the adaptation to rapid changes in the transmission power of the transmitter, i.e. to variations of charge in the output of the transmitter power supply. In the solution according to the invention, the response of the power supply is not dependent on the clock frequency of the power supply control unit, due to which the clock frequency of the power supply control unit can be low. This is why the efficiency achieved by means of a power supply is considerably better than in the prior art solutions. An advantage of the invention is also that the response of parallel power supplies can be easily controlled.